--- In [email protected], "georgiaskywarn" <[EMAIL PROTECTED]> wrote: > > Ok on both from both Kevin's. > > Do have a preamp in line. Will try it out. > > Now...can the test set not be used as a "scale" with a weak signal to > "touch up" the rx side of the dup.s? Not wanting to mess with the > front end of the receiver. Are you also saying I should see something > on meter setting 4+? > > Is "tweaking" the cans not possible with the test set? > Robert > KD4YDC > Robert,
Position 4 if I remember correctly is the discriminator position, and should not be used for signal strength indication. What you are asking about "tweaking the cans" depends on what type of duplexer you have. If it is a pass or pass/notch duplexer, you may be able to rock the pass tuning rods 5 to 10 degrees max to hear or see a difference. Preferably with a very weak signal. If you need to move the adjustment more than that, you have some more serious problems. Do not do this if you have a notch only duplexer. Also you can try and rock the transmit pass adjustments with a wattmeter in line, the same 5 to 10 degrees and see if the transmit power increases any. Often times if it is desense you are fighting by fine tuning the transmitter pass side you are also helping the receiver notch. Most duplexer tuning instructions caution you to not touch the notch of either side while transmitting, this is most often a recipe for disaster. If you decide to twist on the duplexer make sure you have the preamp and all the proper cables in place or the tuning could change once you put the preamp back in. Sounds like you have a catch 22 situation, you need the preamp out to get a good valid meter position 5 indication and you need the preamp in to make sure it does not change the duplexer tuning when in-line. Depending on which brand of preamp you are using, you may or may not see a change. Some of them look pretty ugly on a return loss bridge, and may not present a true 50 ohm impedance to the duplexer or receiver. A better way to do this is with a signal generator connected to a isolated tap or a isolated tee fitting on a wattmeter that is connected to the output of the duplexer and the antenna. Good Luck, Joe - WA7JAW
